Refrigerating apparatus with hot gas defrosting means



y 12, 1953 H. MALKOFF ETAL 2,637,983

REFRIGERATING APPARATUS WITH HOT GAS DEFROSTING MEANS Filed Aug. 22,1950 2 Sheets-Sheet 1 CDCD IN V EN TORS mom 5 V H. MALKOFF ET AL May 12,1953 REFRIGERATING APPARATUS WITH HOT GAS DEF'ROSTING MEANS Filed Aug.22, 1950 2 Sheets-Sheet 2 U U U U U U U U INVENTORS association with theother elements of the apparatus, and located therewithin by any suitablesupports is an element I5 which is shown in the present instance asconsisting of a coil of copper pipe filled with a heat holding substancesuch as a fusible salt of the proper crystalline form, for example,sodium sulphate (a satisfactory crystalline structure of sodium sulphatebeing ten molecules of Water to one molecule of sodium sulphate), leadacetate, ferric nitrate, or calcium chloride; the ends of the pipe coilI5 being closed. Such substances are well known as having low fusionpoints and their function in this apparatus is to serve as a constantsource of held heat. Sodium sulphate, which we prefer for this purpose,has a fusion or melting point of about 93 F. and, when its temperatureis reduced a single degree by transfer of heat the amount of heattransferred is equal to about 90 B. t. u. per pound of the salt. Theother substances named are capable of fusing in a similar manner buthave different fusion points.

One end of easing I4 has an orifice I6 formed therein through whichpasses the end of suction conduit 9 with a fluid tight fit, a suitablestuffing box (not shown) being provided for this purpose if necessary.The extremity of said conduit 5 is downwardly turned, as indicated atI1, in order to discharge the fluid passing therethrough into the lowerpart of casing I4. Another orifice I8 is formed in the said end ofcasing I4 for similarly accommodating a continuation I9 of the suctionconduit 9 which leads to the inlet of the compressor I, as indicated at20. The extremity of conduit I9 within the casing I4 extendssubstantially to the opposite end of the casing and is upwardly turned,as indicated at 2 I, so as to draw from the upper portion of the casing.It will be observed that a part of the suction conduit as it approachesthe casing I4, which part is denoted by 22, lies alongside in contact,or at least in heat exchange relation with, a part of the hot gascompressor discharge conduit, which part is denoted by 23; whereby thesaid part 22 of the suction conduit, and the fluid passing therethrough,are heated by the part 23 of the hot gas line as the fluid flows fromevaporator 4 to casing I4 so that the fluid may attain a temperatureadequate to fuse the substance within coil I5.

A branch conduit 24 leads from the compressor hot gas refrigerantdischarge conduit 5 to the drip pan coil 25 of the evaporator 4 andtherefrom through another conduit 26 to conduit 8 at a pointintermediate expansion valve 1 and the evaporator. In the said conduit24 is positioned a solenoid valve 21 which is in electric connectionwith a source of current and a timing device (not shown but of any wellknown or approved form) for the purpose of periodically opening andclosing the said valve. It will be clear that, when the valve 21 isopened, the hot gas from the compressor discharge will pass throughconduits 24, 26 and 8 directly to the drip pan coil and evaporator coilof the evaporator 4, instead Of passing through the condenser 2, andthat the said hot gas thus passing directly to the evaporator will serveto defrost the said coils thereof in a well understood manner.

In normal operation, the solenoid valve 21 is closed, and therefrigerant gas from the discharge of compressor I passes throughconduit 5, condenser 2, in which it is liquefied, receiver 3, conduit 6,expansion valve 1, and conduit 8 into the evaporator 4 where it servesthe purpose of chilling the refrigeration chamber in which theevaporator is located. This operation revaporizes the refrigerant and itflows through suction conduit 9 into casing I4 and from there throughthe portion I9 Of the suction conduit to the inlet 20 of compressor I.As this fluid flowing through the suction conduit from evaporator tocompressor is in the form of gas or vapor, it will at once rise from thedischarge I1 within the casing I4 to the intake 2| without beingsubstantially affected by the heat holding substance in coil I5.However, if there is any liquid entrained with this gas, it will bevaporized by reason of the contact or juxtaposition of the part 22 ofthe suction conduit 9 with the part 23 of the hot gas discharge conduitas well as by the heat within casing I4 due to the presence therein ofthe heat holding substance.

When a defrosting period arrives, solenoid valve 21 will be opened bythe automatic electric timer (not shown) and the hot refrigerant gaswill then pass from the compressor discharge directly to the evaporator,as hereinabove described, for defrosting the latter. This defrostingstep will liquefy the gas, at least in large part, so that the fluidreturning through suction conduit 9 will be mainly, if not entirely, inliquid form. This liquid will, however, be revaporized in part by theheat exchange relationship of the portion 22 0f the suction conduit withthe portion 23 of the hot gas conduit, but chiefly by heat transferredto the liquid refrigerant by the heat holding substance in coil I5. Theliquid flowing from outlet I1 will drop to the bottom of the casing I4where it will be vaporized by the coil I5, following which the vaporwill rise and be drawn in through inlet 2| of portion I9 of the suctionconduit and carried back to the inlet of the compressor. The heatcontent of the substance in coil I5 is maintained by the fact that,during normal refrigerating periods, the refrigerant vapor returningfrom the evaporator through suction conduit 9 passes in heat exchangerelationship with a portion of the hot gas conduit from the compressordischarge and thus picks up sufficient heat which is imparted to thecoil I5 when the gas is emitted from outlet I1.

It should be observed that, as will be clear to those familiar with thisindustry, the electric timer for controlling solenoid valve 21 may beset to become effective at any predetermined spacing of periods and forany predetermined duration; and that it will also be electricallyconnected with motor I3 so that the evaporator fan 12, which is inoperation during refrigeration periods for circulating air, will bestopped during defrosting periods when solenoid valve 21 is opened. Itmay also be mentioned that a pipe 28 is connected with the drip pan ofthe evaporator 4 in order to drain off to a sewer or other disposalpoint the water received by the drip pan during defrosting, the saidpipe 28 being in practice positioned close enough to pipe 24 toestablish heat exchange relation and. prevent freezing.

Turning now to the modified form of the invention shown in Fig. 2, thecompressor I, condenser 2, receiver 3, evaporator 4, conduit 6, expanionvalve 1, conduit 8, suction conduit 9, feeler bulb I 0, capillary tubeII, fan I2, motor I3, suction conduit portion I9, drip pan coil 25,conduit 26, solenoid valve 21, and drip pan pipe 28, are the same andfunction in the same way as the corresponding parts shown in Fig. 1 andhereinabove described.

The casing I4 and the heat holding coil are also substantially the samein construction as in tion conduit connecting the outlet of theevaporator with the inlet of the compressor for returning refrigerantfrom the former to the latter, a casing positioned in said suctionconduit with the suction conduit entering the casing at a lower partthereof and leaving the casing at an upper part thereof, and a fusibleheat holding substance positioned within said casing intermediate thepoints at which the suction conduit enters and leaves the casing, theparts being so constructed and arranged that the refrigerant flowingthrough the suction line surrounds the said heat holding substance inheat exchange relation therewith while passing through said casing fromits point of entry to its point of leaving.

6. Refrigerating apparatus comprising, a compressor, a condenser, anevaporator, a conduit connecting the discharge of the compressor withthe condenser and with the evaporator for conducting hot gas to theinlet of the condenser during refrigerating periods and to the inlet ofthe evaporator during defrosting periods, a suction conduit connectingthe outlet of the evaporator with th inlet of the compressor forreturning refrigerant from the former to the latter, a casing positionedin the said suction conduit, a portion of the hot gas conduitintermediate the compressor and the condenser being located within thecasing, and a fusible heat holding substance also within said casing,the parts being so constructed and arranged that the refrigerant flowingthrough the suction line empties into the casing and surrounds the saidheat holding substance and the said portion of the hot gas conduit as afluid in heat exchange relation therewith while passing through saidcasing.

'7. Refrigerating apparatus comprising, a come pressor, a condenser, anevaporator, a conduit connecting the discharge of the compressor withthe condenser and with the evaporator for conducting hot gas to theinlet of the condenser during refrigeratin periods and to the inlet ofthe evaporator during defrosting periods, a suction conduit connectingthe outlet of the evaporator with the inlet of the compressor forreturning refrigerant from the former to the latter, a casing positionedin the said suction conduit, a portion of the hot gas conduitintermediate the compressor and the condenser being in the form of acoil and located within the casing, and a fusible heat holding substancealso within said casing contained in at least one hollow coil composedof heat conducting material intertwined with the coiled portion of thehot gas conduit, the parts being so constructed and arranged that therefrigerant flowing through the suction line surrounds the said heatholding substance in heat exchange relation therewith while passingthrough said casing.

HYMAN MALKOFF.

OTTO J. NUSSBAUM.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 168,501 Jas Oct. 5, 1875 336,952 Schmitz Mar. 2, 1886 534,859Cook et a1. Feb. 26, 1895 2,049,625 Ruppricht Aug. 4, 1936 2,440,146:Kramer Apr. 20, 1948 2,531,315 Wythe, Jr. Nov. 21, 1950

